1. Field of the Invention
The present invention relates to an electromagnetic relay, more particularly to an electromagnetic relay including an armature component supported pivotally at a middle portion thereof.
2. Description of the Related Art
Referring to FIGS. 1 and 2, U.S. Pat. No. 4,881,053 discloses an electromagnetic relay 1 including a casing 11, an electromagnet block 12 and a base 13 sealed in the casing 11, and an armature block 135. The electromagnet block 12 includes a spool 121, two pairs of junction terminals 123 having coil winding portions 122 exposed from opposite longitudinal sides of the spool 121, and coils 124 wound on the spool 121. Each of the coils 124 has one end that is to be wound on one of the coil winding portions 122 of the corresponding pair of the junction terminals 123, and the other end that is to be wound on the other one of the coil winding portions 122 of the corresponding pair of the junction terminals 123. The base 13 includes a base body 131 for accommodating the electromagnet block 12, a pair of common terminals 132 and two pairs of fixed contact terminals 133 inserted into the base body 131 and spaced apart from each other, and two pairs of coil terminals 134 connected respectively and electrically to the junction terminals 123. The armature block 135 is connected electrically to the common terminals 132, and is supported pivotally by the electromagnet block 12.
When the armature block 135 is affected by an electromagnetic field generated by the electromagnet block 12, the armature block 135 is brought into contact with left fixed contacts, so as to establish electrical connection between the common terminals 132 and the left fixed contact terminals 133 while breaking electrical connection between the common terminals 132 and the right fixed contact terminals 133. When the electromagnetic field is not generated, the armature block 135 is brought into contact with right fixed contacts, so as to establish electrical connection between the common terminals 132 and the right fixed contact terminals 133 while breaking electrical connection between the common terminals 132 and the left fixed contact terminals 133. Therefore, the electromagnetic relay 1 can serve as a switch unit.
However, because the coil winding portions 122 of each pair of the junction terminals 123 project from the spool 121 away from each other, the size of the base body 131 is relatively large in order to accommodate the entire electromagnet block 12. Moreover, since there is no mechanism for fixing the electromagnet block 12 in the base body 131, it is difficult to connect the junction terminals 123 accurately to the coil terminals 134 during assembly. Further, the common, fixed contact, and coil terminals 132, 133, 134 are manually welded on both sides of the base body 131, so that the electromagnetic relay 1 cannot be fabricated at a high rate.